In a marketing move, Nokia is trying to approach the 3D printing community by releasing files that will let users of the Lumia 820 smartphone to create their own custom shells.

The Lumia 820, announced last September, uses an interchangeable shell that allows users to wirelessly charge their device and choose between a number of colors, which now can be expanded upon with the option to print custom shells.

Nokia is also offering users 3D templates, case specs, recommended materials and best practices to all those who want to design their own shells. Mechanical drawings in either STL or STP file formats can be downloaded from the company's developer website.

Printing in 3D involves sending a design file to a printer that then forms a solid version of that object by slowly building it up in layers of plastic. Early 3D printers could only work in one colour but the latest versions can produce intricate, multicoloured objects.

Nokia 's "3D printing development kit" will help people produce the cases. To get the files, users must have registered with Nokia.